A majority of the cars and trucks in use today utilize water-cooled engines. The cooling system of such engines employs flow paths within the engine block, a water pump, and a radiator through which a cooling medium such as water or antifreeze circulates under pressure. The water pump is usually mounted on the front of the engine and connects to the flow paths in the engine and to the lower of the two hoses typically passing from the radiator. The upper radiator hose connects directly to the flow paths in the engine block. In this manner, a complete flow path through the engine and radiator for the cooling medium is created. A thermostat is usually used within the flow path to restrict circulation of the cooling medium when the engine is operating below the desired temperature.
Within the cooling system of most vehicles is a heater which connects between the flow paths in the engine block and the water pump. Hot water passes from the engine block into the heater and then returns into the water pump.
The amount of pressure developed in such cooling systems depends to a large extent on the temperature of the coolant and the speed at which the engine is operating. Thus, at high speed, or when the coolant is at a high temperature, such as when the vehicle is idling in traffic, the pressure of the cooling medium can be very high. Since the cooling system is designed to be a closed system, any minor leaks present in the system may result in excessive loss of coolant when the pressure in the system begins to rise. As the cooling medium is lost through such leaks, the capability of the cooling system to keep the engine temperature from rising above a normal operating level begins to decrease. If enough of the cooling medium is lost, the engine could overheat, with subsequent damage to the engine.
It is thus well-known that the cooling systems of water-cooled internal combustion engines should be pressure-tested periodically in order to detect the presence of leaks therein. The devices found in the prior art for testing the cooling systems of vehicles typically fall into two groups. The first of these groups are devices which are designed to simply test the radiator and/or the radiator filler cap. Such devices usually comprise a small air pump and gauge. When these devices are used to check the radiator filler caps, the cap is connected directly to the device, air is pumped into it, and the gauge reading is observed as the valve in the filler cap opens. When these devices are utilized to check the radiator, the filler cap is removed from the radiator, and the radiator inlet and outlet ports are sealed. Pressure is then applied to the radiator until the radiator is at its rated pressure level. If no air escapes from the radiator, it is presumed to be working properly.
The other group of devices are those designed to test the cooling system as a whole. In such devices, pressure is applied to the complete cooling system via a special radiator cap or, for example, by special conduits which connect to the heater connections on the engine. The cooling system of the engine is then pressurized with air via an air pump or an external source of compressed air and the pressure capacity of the cooling system is observed as a gauge.
None of the devices in the two groups described above allows testing of only the portion of the cooling system within the engine, i.e., the flow passages in the engine block and the water pump. In vehicles which are rather old, or which have been subject to a freeze-up, the cooling system may have leaks at both the radiator and within the engine block. The pressure testing devices which check only the radiator, or which check only the radiator when connected to the rest of the cooling system will not normally detect the leaks within the engine block, as the radiator leaks will be the ones that are immediately apparent when pressure is applied to the cooling system. Thus, the ability to test the cooling system with the radiator removed readily facilitates the pinpointing of a leak in the cooling system within the engine.
Additionally, many of the devices in the prior art require the use of a manual hand pump for the insertion of the pressure into the system and lack any means to automatically release the pressure past a certain predetermined level to avoid damaging the cooling system components. Also, as described, the devices found in the prior art are generally restricted to testing either the radiator and the filler cap or the cooling system as a whole, and do not have the capability to individually test each portion of the system. It would be most convenient, therefore, to provide a device which not only separately checks each individual portion of the cooling system, but which also utilizes air from an external source of compressed air, and further includes a pressure relief valve to release the pressure in the cooling system when the system is being tested to avoid damage to the cooling system components when the pressure reaches a predetermined level.
Accordingly, it is an important object of this invention to pressure test the cooling system of an internal combustion engine with the radiator and heater portions of the system disconnected.
It is an additional object of this invention to perform such pressure testing, and the comprehensive testing of the remainder of the cooling systems, in a simple and uncomplicated manner, and using a mimimum number of parts.
It is a further object of this invention to separately test the radiator, the radiator filler cap, and the portions of the cooling system within the engine.
It is still another object of this invention to pressure test the various components of the engine through the use of an external source of compressed air.
It is a final object of this invention to allow the manual release of the pressure in the cooling system under test when the test has been completed, and to allow the automatic releasing of pressure from the cooling system under test when a predetermined level of pressure has been surpassed.